Calcium-phosphate-silicate composite bone cement: self-setting properties and in vitro bioactivity

In this study, a novel low temperature setting calcium phosphate-silicate cement was obtained by mixing CaHPO(4) x 2H(2)O (DCPD) and Ca(3)SiO(5) (C(3)S) with 0.75 M sodium phosphate buffers (pH = 7.0) as liquid phase. The self-setting properties of the obtained DCPD/C(3)S paste with liquid to powder ratio (L/P) of 0.6 ml/g, such as setting times, injectability, degradability and compressive strength were investigated and compared with that of DCPD/CaO cement system. The results indicated that, with the weight ratio of C(3)S varied from 20% to 40%, the workable DCPD/C(3)S pastes could set within 20 min, and the hydrated cement showed significantly higher compressive strength (around 34.0 MPa after 24 h) than that of the DCPD/CaO cement system (approximately 10.0 MPa). Furthermore, the in vitro pH value of the cements was investigated by soaking in simulated body fluid (SBF) for 12 h, and the result indicated that the DCPD/C(3)S did not induce significant increase or decrease of pH value in SBF. Additionally, the composite cement possesses better ability to support and stimulate cell proliferation than the DCPD/CaO cement. With good hydraulic properties, improved biocompatibility and moderate degradability, the novel DCPD/C(3)S bone cement may be a potential candidate as bone substitute.